The present invention relates to a method for making a firmly-bonded connection of an electronic component to a substrate, a solder paste used in this method, and an arrangement that can be obtained in this method.
WO 2011/009597 A1 discloses a method for the firmly-bonded connection of an electronic component to a substrate, comprising a) providing an electronic component having a first surface to be connected and a substrate having a second surface to be connected, b) applying a solder paste to at least one of the surfaces to be connected, c) arranging the electronic component and the substrate appropriately such that the first surface of the electronic component to be connected and the second surface of the substrate to be connected contact each other by the solder paste, and d) soldering the arrangement from c) in order to generate a firmly-bonded connection between the electronic component and the substrate. The thickness of the applied layer of solder paste is at least 20 μm. The solder paste used in the method contains (i) 10-30% by weight (percent by weight) copper particles, (ii) 60-80% by weight particles made of at least one substance selected from the group consisting of tin and tin-copper alloys, and (iii) 3-30% by weight solder flux, wherein the mean particle diameter of the copper particles and of the particles made of at least one substance selected from the group consisting of tin and tin-copper alloys is ≤15 μm.
The applicant has noted that the method known from WO 2011/009597 A1 can be used, surprisingly, to obtain further improved soldered connections, in particular more reliable soldered connections under high temperature conditions in the range of, for example, 250 to 300° C., by using as copper particles in the solder paste particles made of copper and/or of copper-rich copper/tin and/or copper/zinc alloys, which each have a phosphorus content >0 to ≤500 wt-ppm.